The proposed 12-month project research addresses the interaction of treatment services and therapies and client outcomes in the treatment process. It will use existing data collected in the Treatment Outcome Prospective Study (TOPS). The proposed model is based upon event-history methodology, which takes into consideration the number, timing, and sequence of changes in the dependent variables (outcomes) within a fixed period of time. The event-history methodology technique which will be the basis of the research is a discrete-time procedure modeling the discrete-time hazard rate in terms of explanatory variables. The outcome variables will be put in the form of discrete time hazard rate variables and the treatment services will be explanatory variables in the models analyzed. The outcome variables to be considered include drug use, alcohol use, depression, and employment during treatment. The treatment service variables will be time-dependent. The models will also take into consideration the needs of the clients in the analyses since the needs will have a bearing on the services given. Other components of the model include background characteristics of the clients, static measures describing the treatment environment, and satisfaction with the treatment.